1. Field of the Present Invention
The present invention relates to an ink cartridge that is mounted on an ink-jet recording apparatus, and to an ink-jet recording apparatus having mounted thereon an ink cartridge.
2. Description of the Related Art
In an ink-jet recording method, for the sake of high printed image quality and high printed character quality (hereinafter, collectively referred to as high print quality), accurate control of ejection of fine droplets having a volume of several picoliter from fine ejection nozzles is demanded. Accordingly, it is necessary to prevent a foreign substance from entering into and interfering with the flow of ink in a portion of an ink-jet recording apparatus that comes into contact with ink (hereinafter, the portion being also referred to as an ink flow passage).
In order to prevent the foreign substance from being clogged in the ink flow passage of the nozzles or an ink-jet recording head (hereinafter, simply referred to as head), countermeasures are taken, such as assembling of parts of the ink flow passage and the preparation of ink in a clean room, and the filtration of ink using a fine filter having a pore size of less than 1 μm. In addition, there is suggested a technology that, before ink for ink-jet recording is introduced into the head, prevents a foreign substance from flowing into the head by providing a filter in the ink flow passage (Japanese Patent Application Laid-open No. 2002-67312).
When such a filter is provided, if ink is stored in an ink storage chamber of an ink cartridge, precipitate occurs in ink, and thus the filter may be closed. In particular, when wide area printing that requires a large volume of ink is performed, the filter tends to be markedly closed.
The reason why the precipitate occurs while ink is stored in the ink cartridge is considered as follows. Generally, as a resin material for the ink cartridge, polyolefin resin that is cheap and can be easily processed is used, and a crystal-nucleating agent (sorbitol or the like) is mixed in the resin material for the sake of improving moldability or transparency. For this reason, when the resin material constituting the ink storage chamber of the ink cartridge continues to be in contact with ink for a long time, the crystal-nucleating agent may be eluted from the resin material and then become the precipitate.
As such, when the precipitate occurs in the ink storage chamber of the ink cartridge, the precipitate is accumulated on the filter, and an ink supply to a pressure chamber is unstable, such that ink is not ejected. Further, when ink that passes through the filter stays in the head for a long time, the precipitate may be grown. In this case, the ejection of ink droplets becomes unstable due to clogging of the ink flow passage or the nozzles. For this reason, if the precipitate resulting from the ink storage chamber of the ink cartridge occurs in ink, it is difficult to keep high print quality.
Accordingly, as the resin material constituting the ink storage chamber of the ink cartridge, there is no choice but to use a resin material that does not contain a crystal-nucleating agent as the cause of precipitate.
When the ink storage chamber of the ink cartridge is formed of a resin material not containing a crystal-nucleating agent, the precipitate resulting from the crystal-nucleating agent is prevented from occurring. In this case, however, moldability is degraded and many voids occur, or transparency is degraded. If the transparency of the ink storage chamber is degraded, in order to detect an ink residual quantity in the ink storage chamber, a transmissive ink detection sensor having a relatively complex structure has to inevitably be used, instead of a reflective ink detection sensor having a relatively simple configuration. In addition, in order to apply the transmissive ink detection sensor, the shape of the ink cartridge needs to be changed. Therefore, even if the crystal-nucleating agent is not used, it is necessary to select a resin material that can maintain moldability or transparency to some extent. As such, when the ink storage chamber of the ink cartridge is formed of the resin material not containing the crystal-nucleating agent, a degree of freedom of selecting the resin material for the ink storage chamber is degraded, and the structure of the ink cartridge or the ink-jet recording apparatus is complicated. Further, manufacturing costs of the ink-jet recording apparatus are increased.